Preheat oven to 375 degrees F. Lightly spray a 9x11 baking dish with cooking spray; set aside.
In a large bowl toss blueberries, cornstarch, sugar, salt and vanilla together. Pour into prepared dish.
Top blueberries evenly with the crumb mixture. Bake for 35-40 minutes or until bubbly and topping is golden brown.
If using frozen blueberries there's no need to thaw before baking.